Radiation Effects On DNA: Theoretical Investigations Of Electron, Hole And Excitation Pathways To DNA Damage

Radiation induced DNA damage is the most significant biological effect of radiation. Initially, radiation interacts with each component of DNA randomly resulting in DNA holes, electrons and excited states. Holes and electrons undergo rapid transfer to the most stable sites followed by proton transfer processes. These initial effects depend on the fundamental properties of DNA such as ionization potentials and electron affinities which are amenable to high level ab initio theories such as density functional theory. In this review, the recent theoretical treatments of these likely radiation intermediates are discussed. Topics include DNA base and base pair electron affinities, ionization potentials, proton transfer processes, solvation effects on the electron affinity of bases and base pairs, the role of low energy electrons (LEEs) in DNA damage, and sugar radical formation from hole excited states. These results clearly show a role for molecular orbital theories in developing a full explanation of the radiation damage processes